The present invention relates to an axially-displaceable and angularly-movable, evenly-running universal coupling, in which the torque is transmitted by three rolling parts which are distributed equiangularly. The rolling parts are connected to the inner part of the coupling in a rotatable and radially movable manner. The rolling parts, furthermore, project into grooves in the outer part of the coupling, which are straight and parallel to the axis. To achieve even running, the displacement of the rolling parts required during an angular movement is accomplished with the aid of a force, pushing the rolling part outward. This force is a spring derived or spring-actuated force.
Universal couplings of the preceding species and known in the art, have the inner part of the coupling constructed of three-legged form. In this arrangement, so-called thrust stones are supported on the corresponding studs, in a slidable and rotatable manner for torque transmission. In contrast to the prior art, in which the thrust stones are coated with relatively thin discs of elastic material, an arrangement disclosed in the German Patent No. 2,216,345 operates in the following manner: For exerting an outward-directed force on the thrust stones, a ring is provided on one or both sides of the three-legged structure. This ring is in contact with each of the thrust stones when force is exerted parallel to the axis of each.
The difficulty of arriving at an effective solution with the aid of elastic discs, in the prior art, has been extensively described in a review of the state of the art in the German Patent No. 2,216,345. The arrangement disclosed by this German patent, has the disadvantage of requiring costlier construction and manufacture, and it is also associated with the danger that breakage of the highly-stressed rings could cause the pieces to destroy the universal coupling.
The two arrangements above of the prior art, also have the common disadvantage that the relatively large controlling force applied by the spring elements, does not act near the center of the axis of rotation of the thrust stones. Instead, the force acts substantially far out therefrom. A large braking torque results, thereby, and the thrust stones, prevented from rotating, cause wear, heating, and ineffectiveness.
Accordingly, it is an object of the present invention to provide a universal coupling of the character described above, and which avoids the disadvantages mentioned supra.
Another object of the present invention is to provide a universal coupling of the foregoing character, which is simple in design and may be economically fabricated.
A still further object of the present invention is to provide a universal coupling, as described, which has a substantially long operating life and may be readily maintained.